The 16S rRNA high-throughput sequencing analysis was conducted on the rhizosphere soil of Cassava South China No.12 under treatment without fertilization (CK), organic fertilizer (T₁), conventional fertilization applied with organic fertilizer (T₂), and reduced chemical fertilizer applied with organic fertilizer (T₃) by using the Illumina Nova 6000 sequencing platform to study the effects of chemical fertilizer application combined with organic fertilizer on the growth of cassava and the bacterial diversity and community structure in cassava rhizospheric soil. T₃ not only significantly increased the height and stem thickness of cassava, but also improved the yield of cassava, compared to CK. Cluster analysis was performed on the sequences based on 97% similarity, the OTUs numbers of CK, T₁, T₂ and T₃ are 3603, 1688, 1276 and 3317 respectively. Different fertilization methods altered the diversity and richness of soil bacteria, with the species diversity ranked from highest to lowest as CK>T₃>T₁>T₂. Based on PCoA and cluster analysis, the community composition of CK and T₃ was similar, the community composition of T₁ and T₂ was similar. The dominant phylum in cassava rhizospheric soil under different fertilization treatments were Proteobacteria, Bacteroidetes, Acidobacteria, Firmicutes, Actinobacteria and Chloroflexi. The relative abundance of Proteobacteria, Bacteroidetes and Actinobacteria increased under T₃ treatment, while the relative abundance of Firmicutes and Chloroflexi decreased. Redundancy analysis results indicated that available potassium was the main factor affecting the bacterial community in the cassava rhizosphere soil. In summary, the study demonstrates that reduced chemical fertilizer application combined with organic fertilizer not only increases the yield of cassava, but also changes the community structure and diversity of the bacterial in the rhizosphere soil. The results would provide a solid theoretical foundation for the development of a green, efficient, and sustainable cassava industry.

The study was aimed to explore the resistance to Colletotrichum siamense, dominant specie of rubber tree induced by Burkholderia arboris DHR18. The enzyme activity changes on the treatments of different concentrations of DHR18 fermentation broth and co-treatments of DHR18 with C. siamense CH-1 using rubber clone GT1 were studied. Five defensive enzymes including catalase (CAT), peroxidase (POD), phenylalanin ammonialyase (PAL), and superoxide dismutase (SOD) were assayed. Results indicated that treatments with 1×10⁸ CFU/mL, 1×10⁷ CFU/mL, 1×10⁶ CFU/mL of DHR18 fermentation broth showed significant higher activities of CAT, POD, PAL, SOD and PPO in rubber leaves compared to the control group. The enzyme activities with broth concentration 1×10⁷ CFU/mL were the highest. The activity peak of the five enzymes was 1 009.14, 29 138.67, 110.24, 902.42 and 148.00 U/g, respectively, which was 2.68, 3.35, 1.88, 3.97 and 4.51 times of the control group, respectively. Under the co-treatments of B. arboris DHR18 and C. siamense CH-1, treatment group inoculated with DHR18 fermentation broth before inoculated with CH-1, the enzyme activities were higher than other co-treatment groups, and significantly higher than that of the control group. Activity peak of CAT, POD, PAL, SOD and PPO was 1 230.85, 45 504.67, 117.53, 1 342.17 and 134.40 U/g, respectively. They were 4.56, 3.10, 2.04, 3.28 and 5.98 times that of the control group, respectively; The plate inhibition rate of strain DHR18 against C. siamense was 71.56%, the preventive effect against C. siamense on rubber saplings was 81.79%, and the control effect was 44.35%. The results showed that Burkholderia arboris DHR18 could promote the activity of defense-related enzymes in rubber trees and induce systemic resistance in rubber trees. The induced resistance may be one of the reasons for the control of C. siamense by B. arboris DHR18.

This study aims to screen the microbial strains capable of producing β-D-glucosidase from fermented vanilla pods and apply the screened strains to the fermentation process of vanilla with the goal of enhancing vanillin production and improving the quality of vanilla bean. Septenary selective medium was utilized to isolate β-D-glucosidase producing bacteria, identify the homology of each bacterial strain and measure the production of β-D-glucosidase activity of each strain on two strains with higher enzyme production. The phylogenetic tree was constructed. The two strains of bacteria with the highest enzyme production in different combinations were sprayed onto the fermented vanilla pods. The content of vanillin, vanillin glucoside, and volatile components in different treatments of β-D-glucosidase producing bacteria were determined. Nine strains were successfully screened from the vanilla pods originating in Madagascar (M), and twelve strains were isolated from the vanilla pods produced by Spice and Beverage Research Institute, Chinese Academy of Tropical Agricultural Sciences (S). The fifteen strains were detected as Bacillus. M3 and S7 had higher enzyme activities than other isolates. Vanilla pods treated with M3 obtained the highest vanillin content, which reached to 2.25% and possed the highest aroma components. The maximum decrease in vanillin glucoside content was 80.7% when sprayed with M3 and S7 in a volume ratio of 1:1. There were 34 volatile substances in the fermented pods sprayed with M3, making it the most volatile combination of spraying bacteria. In the present study, we successfully isolated β-D-glucosidase producing bacteria for improving the quality of vanilla pods fermentation.

Sisal hybrid variety of H.11648 is the main cultivated commercial variety in China. Despite of its ability to produce high fibre yield per unit area, this variety is highly susceptible to diseases. Sisal zebra disease, caused by Phytophthora nicotianae is among the diseases of economic importance affecting the variety. Several control measures like the adoption of good agricultural practices, the use of disease resistant variety and the use of chemical control are suggested in sisal zebra disease control. However, none of them seem to be sustainable due to the existing agricultural practices. Most of the existing measures are not only time-consuming but also costly due to labor intensification and high cost of purchasing agricultural chemicals which on another hand can pollute the environment and create resistance to the plants. Developing resistance variety will obviously take long time due to the long life cycle of sisal. It is very important to develop sustainable disease control methods which are environmental friendly to adopt the climate change agenda. The use of microorganisms to control the diseases is of great importance. In this study, an antagonistic strain PaHNHK01 was successfully isolated by using Phytophthora nicotianae as the target pathogen. PaHNHK01 was identified as Pseudomonas aeruginosa based on morphological, physiological and biochemical characteristics and gene sequence analysis. The antibacterial activity and control effect of PaHNHK01 were measured under in vitro condition. The results showed that, PaHNHK01 had the ability of organophosphorus and inorganic phosphorus, nitrogen fixation and iron production. Additionally, PAHNHK01 had the inhibition rate of 89.79% against P. nicotianae. The fungus effectively inhibited the mycelial growth of P. nicotianae, and the antagonistic pathogens showed decreased sporulation ability, mycelial enlargement deformity and increased branching. The control effect of PaHNHK01 on sisal zebra disease in vitro was 88.62%. PaHNHK01 aseptic fermentation liquid had obvious bacteriostatic effect on pathogenic bacteria, and its EC₅₀ value was 20.3679 μL/mL. When the concentration of PaHNHK01 crude extract was 80 μg/mL, the antibacterial rate was 89.36%, and the EC₅₀ value of PaHNHK01 crude extract was 11.9456 μg/mL. We further observed the antagonistic effects of the strain PaHNHK01 on 13 different plant pathogens, indicating that the strain PaHNHK01 had good biocontrol potential and could be developed as a biocontrol product. The results would provide a strong research basis for the biological control of sisal zebra disease.

The microbial community of fruit peel tissues helps to improve fruit quality and resistance to pathogens. There are few reports on the community structure and diversity of endophytic microbes of pitaya peel tissues. This study analyzed the composition and diversity of the endophytic microbial communities in the peel tissues of young healthy fruits and diseased fruits at the early stage of canker disease, and predicted microbial functions to understand the characteristics, through Illumina MiSeq high-throughput sequencing technology. The results showed that there was no significant difference in the diversity and structure of the endophytic bacterial and fungal communities between healthy and diseased peel tissues of pitaya young fruits. In the peel tissues of healthy fruits, Proteobacteria, Actinobacteriota, Firmicutes, Bacteroidota, Deinococcota, Desulfobacteriota and Chloroflexi were the dominant bacterial phyla, and Ascomycota, unclassified_k_Fungi, Basidiomycota and Mucoromycota were the dominant fungal phyla. In the early stage of canker disease, the bacterial phyla Proteobacteria, Actinobacteriota and Deinococcota, as well as fungal phylum Ascomycota, significantly decreased, while bacterial phylum Desulfobacteriota and fungal phylum unclassified_k_Fungi significantly increased in average relative abundance. Compared with the healthy fruits peel, with differences in the proportion of the above microbes, the expression levels of chemoheterotrophy, aerobic chemoheterotrophy, methylotrophic and methanol oxidation functions of endophytic bacteria in diseased fruits peel significantly decreased, the proportion of potentially_pathogenic groups of endophytic bacteria significantly increased, the proportion of saprotroph, pathotroph, pathotroph symbiotroph of endophytic fungi significantly decreased, and the proportion of unknown trophic fungi significantly increased. The results would provide biological information on the endophytic microbes in pitaya fruits peel, to reveal the role in the occurrence of pitaya canker disease and provide theoretical basis for utilizing the function of beneficial microorganisms.

The pericarp color, browning-related enzyme activity and variations in phenolic compounds during the browning process of litchi pericarp were evaluated to investigate the alterations in ingredients caused by pericarp browning of two litchi varieties (Guiwei and Yuhebao) during storage. The indicators were comprehensively evaluated using correlation analysis and principal component analysis. The results showed that at a storage temperature of 4 ℃, the pericarp of Yuhebao was more likely to brown than that of Guiwei. After being stored for three days, the pericarp of Yuhebao exhibited noticeable browning, but Guiwei only displayed a similar phenomenon after seven days of storage. Over the period of 0-14 days of storage, both Guiwei and Yuhebao showed a decline in the total phenolic, flavonoid and proanthocyanidin levels in the pericarps due to browning. Both Guiwei and Yuhebao pericarps exhibited an increased trend in pH value, with the lower rise rate in pH value of Guiwei pericarp compared with that of Yuhebao. Additionally, the level of polyphenol oxidase (PPO) activity in the pericarps of both litchis exhibited a declining pattern, with a more pronounced decline observed in Yuhebao compared to Guiwei. The peroxidase (POD) enzyme activity in the two litchi pericarps exhibited a little decline, whereas the POD enzyme activity in the Yuhebao pericarp was approximately 1.33 times higher than that of Guiwei. Correlation analysis and principal component analysis revealed that total phenols, flavonoids, PPO and pH value were found to have a significant correlation with the browning color of the two litchi varieties. There was a noticeable correlation between the selected litchi varieties and the browning process, indicating distinct differences in the browning status of the pericarp. The findings of this study could offer fundamental data support for future research on suppressing the browning phenomena of litchi pericarp, extracting and processing phenolic active compounds from litchi pericarp.

A comparative analysis of the fungal community in the seedling roots of Dendrobium nobile formed by in situ symbiotic seed germination was conducted. The fungal composition and abundance dynamics were investigated to reveal the similarities and differences between the fungal treatments and the control, on three seedling developmental stages based on ITS amplicon sequencing technology and further analysis using QIIME 2 and DADA 2 methods. A total of 1 029 977 valid sequences were obtained and grouped into 876 amplicon sequence variants (ASVs). The fungal treatments had more ASVs than the control, but no significant differences in fungal community richness and diversity. The number of fungal ASVs and the fungal community richness and diversity in seedling roots increased with development, and the Chao1 index was significantly higher at the 6-month seedlings than the 4- and 5-month seedlings. The principal coordinates analysis showed dissimilarities on fungal community between the fungal treatments and the control, and there were significant differences in seedlings at different developmental stages. Fungal ASVs identification showed that the dominant fungal genera in both the fungal treatments and the control were Serendipita and Sebacina, which belong to Sebacinales, while Tulasnella (Tulasnellaceae) was exclusively found in the control. Among the different month-staged seedlings, the relative abundance of the dominant genera, Serendipita and Sebacina, decreased with seedling growth, and the proportion of non-orchid mycorrhizal fungi progressively increased. The research results revealed the dynamics of the fungal communities in the artificial seedling roots of D. nobile, which was of theoretical significance for its reintroduction and ecological recovery.

Tonoplast intrinsic proteins (TIPs), which comprise a subfamily of aquaporin (AQP) mediating the water balance within plant cells, could be divided into five phylogenetic groups on the basis of sequence similarity, i.e., TIP1–TIP5. Based on the full-length transcriptome previously described in tigernut (Cyperus esculentus), a tuber-abundant TIP gene named CeTIP4;1 was cloned and characterized in this study. Sequence analyses revealed that CeTIP4;1 contained two conservative introns with a complete coding sequence of 753 base pairs (bp), putatively encoding 250 amino acids with the theoretical molecular weight of 25.57 kDa, the isoelectric point (pI) value of 6.02, and the grand average of hydropathicity (GRAVY) value of 0.884, implying its acidic and hydrophobic features. The deduced peptide possessed one conservative major intrinsic protein (MIP) domain and exhibited similar structural features with the structure resolved AtTIP2;1. Classification of CeTIP4;1 into the TIP4 group was supported by the phylogenetic analysis, which showed that CeTIP4;1 clusters with AtTIP4;1, OsTIP4;1, OsTIP4;2 and OsTIP4;3 with sequence similarities of 69.62%–82.94%. After gene cloning, a plant expression vector for subcellular localization, i.e., pNC-Cam1304-CeTIP4;1, was successfully constructed. When transiently overexpressed in tobacco (Nicotiana benthamiana) leaves, confocal laser scanning microscopy imaging showed that CeTIP4;1 was unexpectedly localized to the cell membrane. Further expression analysis indicated that CeTIP4;1 exhibited an apparent tissue-specific expression patter, predominately expressed in tuber, root, rhizome, and shoot apex. Moreover, among the four typical stages of developmental tuber examined in this study, i.e., initiation, medium swelling, late swelling, and maturation, CeTIP4;1 exhibited a bell-like expression pattern, peaking in medium swelling tubers and lowest in maturation tubers. These results lay a solid foundation for further uncovering the mechanism of water balance in tigernut tubers.

In order to clarify the situation of macrofungal resources in Haikou, the analysis on species diversity of macrofungi in Haikou was carried out based on the samples collected by the authors in 2022 and deposited in Fungarium of the Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences (FCATAS). A total of 110 species of macrofungi, belonging to 69 genera, 32 families, 10 orders, and 2 phyla, were identified based on morphological and molecular evindence. Two new species, 10 new Chinese records, and 33 new records in Hainan were found. Five dominances with more than 5% in total species were Polyporaceae, Hypoxylaceae, Agaricaceae, Xylariaceae, Omphalotaceae and Pleurotaceae, including 55 species, accounting for 50.00% of the total species. The assessment of the utilization value of the macrofungi showed that there were 8 edible species, 14 medicinal species, and 3 poisonous species in Haikou, indicating the resources have good application prospects. According to the records of “Redilist of China’s Biodiversity-Macrofungi”, 44 species of macrofungi in Haikou were assessed. Among them, Macrocybe gigantea was near to be threatened (NT), 27 species were least concerned (LC), and 16 species were data deficient (DD). The present study would provide important scientific basis for the protection, utilization and management of macrofungal resources in this area.

Pitaya contains abundant nutrients and is highly preferred by consumers. However, this fruit is prone to quality deterioration problems such as yellowing of fruit scales, fruit dehydration, peel shrinkage and decay during the postharvest storage period, which seriously affect its commercial value. Jindu No.1 variety was used to investigate the effect of gibberellin composite chitosan treatment on the postharvest quality and antioxidant capacity of pitaya. Pitayas of uniform size, consistent maturity and intact condition were randomly selected for six types of treatments: water (control group), 5 g/L chitosan, 50 mg/L gibberellin, 25 mg/L gibberellin + 5 g/L chitosan, 50 mg/L gibberellin + 5 g/L chitosan, and 100 mg/L gibberellin + 5 g/L chitosan treatments. The pitayas were stored at a constant temperature of 25 ℃ after treatment, and postharvest quality indicators including lipoxygenase activity (LOX), malondialdehyde (MDA) content, antioxidant substance content and antioxidant enzyme activity were measured regularly. The results showed the well-maintained storage quality of pitayas treated with 50 mg/L gibberellin + 5 g/L chitosan. After 12 days of storage, the rate of fruit scale yellowing and water loss was reduced by 15.91% and 20.75% respectively compared with those of the control. The soluble sugar content, color a^* value and L^* value of the fruit were substantially higher than those of the other groups and the soluble pectin content was considerably lower than those in the other groups. The 50 mg/L gibberellin + 5 g/L chitosan treatment could also maintain the improved antioxidant capacity of pitaya. After 12 days of storage, MDA content and LOX activity in the fruit decreased by 16.04% and 19.23% respectively compared with the control. The content of antioxidant substances such as flavonoids, total phenols, reduced glutathione (GSH) and reduced ascorbic acid (AsA) increased by 10.07%, 10.00%, 31.43% and 12.93%, respectively. The activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased by 17.61%, 79.22% and 15.00% respectively compared with those of the control. The gibberellin composite chitosan treatment with appropriate concentrations could effectively maintain the postharvest quality of pitaya, increase the fruit’s antioxidant capacity, reduce membrane damage caused by lipid peroxidation, delay the ripening and aging of pitaya, and extend the preservation period. In addition, composite treatments could be considered a green, environmentally friendly, economical and effective preservation method that can serve as an application reference for pitaya storage, transportation and preservation industry after harvest.